Fuel injection pump



@Ct 16 3951 c. w. TRUXELL, JR 2,571,501

FUEL. INJECTION PUMP Filed Aug. l', 1945 -IIIHr wulllll IIIH' Patented Oct. 16, 1951 FUEL INJECTION PUMP Clyde W. Truxell, Jr., Grand Rapids, Mich., as-

signor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 17, 1945, Serial No. 610,937

2 Claims. 1

The present invention relates to fuel injection pumps for internal combustion engines.

The principal object of this invention is to provide a simple and inexpensive fuel injection pump including few cooperating elements of simple form to cause circulation through and by-pass of fuel from a pumping space prior to causing the start of fuel injection therefrom through a nozzle and then causing a prompt relief of pressure in this space to cause the finish of injection without after-dribble of fuel from the nozzle.

This and other objects, together with the novel features by which these objects are accomplished, will become apparent by reference to the following description, operation and drawings illustrating two types of fuel injection pumps differing slightly in detail and incorporating these novel features. j

Figure 1 of the drawings is a vertical sectional view of one form of fuel pump.

Figure 2 is a partial vertical elevation view of the pump shown in Figure l taken at right angles thereto and with parts broken away in order to show certain details of this pump more clearly.

Figure 3 is a view similar to Figure 1 of a slightly different form of pump.

Figure 4 is a top plan view of the pump illustrated in Figure 3.

The fuel injection pump shown in Figures l and 2 includes a pump cylinder or body I having an axial cylindrical bore 3, a cylindrical pump plunger 5 movable in one end thereof and an assembly comprising a fuel spray nozzle 1, check valve housing 9 and hollow check valve seat II clamped by means of a cap nut I3 to the cylinder to close off the other end of the cylinder bore 3 land form a pumping space I4 in the bore bejects through the nut I3 and is provided with a n extending diametrically therethrough and forming two ports 21 and 29 opening into the pumping space I4 and enclosed by the filter element I5.

The plunger 5 is urged outwardly of the cylinder bore 3 by a compression spring 3| surrounding the plunger and retained on the outer end thereof by a retaining washer 33 nonrotatably mounted on the plunger by reason of the flat 4| thereon and retained in place by a key 35 located in a slot 36 of the plunger. The inner end of this spring is retained and supported on a flange 31 of a plunger control sleeve 39 which is slidably mounted on and nonrotatably attached to the plunger by means of a flat 4| formed thereon. T-he flange 31 of the control sleeve 39 is carried on a ball thrust bearing 43 supported on a flange 45 of the cylinder I. A control arm 41 integral with the flange 31 of the control sleeve 39, shown in Figure 2, is adapted to be moved angularly by manual control means or a governor to cause rotation of the plunger to vary the amount of fuel injected by the pump by reason of the following control surfaces provided on the inner end of the plunger. A circumferential pressure relief groove 5| is formed on the plunger adjacent the circumferential edge portion 53 of the working face thereof and a slot 55 formed in the plunger extends from this groove to the working face. One edge 5G of this slot is inclined to the axis of the plunger to cooperate with the port 29 and the circumferential edge 53 of the plunger working face coopcrates with the port 21so that upon inward movement of the plunger on the injection stroke the port 21 is closed by the edge 53 prior to closure of the port 29 by the inclined edge 56 and both ports are then uncovered simultaneously by the circumferential edge 51 of the relief groove 5|. The above fuel injection pump is shown mounted in a counterbore 59 in an internal combustion engine cylinder head 6|. An opening 63 extends from the counterbore to the engine combustion space through which the nozzle 1 projects so that fuel is injected into this space through the nozzle spray openings 25. A fuel pressure supply passage is provided in the cylinder head. which passage opens into the counterbore, and another fuel drain and by-pass passage 61 in the cylinder head extends from the counterbore back to a fuel tank, not shown. A gasket 69 is placed on the nozzle 1 and is accordingly positioned between the cap nut and inner end of the counterbore and a second gasket 1| is carried in an annular groove of the cylinder Suitable clamping and positioning means on the cylinder head, as shown, serves to hold the gaskets 59 and 1| under' compression between the surfaces of the pump cylinder and the counterbore of the engine cylinder head to form a fuel space 12 around the pump filter element I and cap nut I3 and to position the ports 21 and 29 of the fuel pump in alignment with the fuel pressure passage G5 and drain and by-pass passage 61, respectively, in the engine cylinder head 6|. Any suitable engine driven actuating and motion limiting means, not shown, may be' provided to cause inward movement and to limit outward movement of the plunger by the spring in timed relation with the engine so that fuel is injected by the pump into the engine combustion space at the proper time in the operating cycle. This actuating and limitlng means should contact the outer end of the plunger in point contact to facilitate angular movement of the plunger relative to the ports 21 and 29.

With the fuel injection pump mounted in the engine cylinder head in the above described manner and with the pump parts in the position shown, the port 21 serves as a fuel pressure inlet port and the port 29 serves as a by-pass and drain port. Fuel under pressure accordingly circulates through the filter element I5, ports 21 and 29 and pumping space I4 from the cylinder head fuel pressure passage 65 to the drain and by-pass passage 61. Fuel also circulates around the cap nut I3. This circulation of fuel causes any vapor in these passages and in the fuel to be carried thereby back to the tank through the drain or by-pass port 29 and passage 61. This insures complete filling of the passages and cooling of the parts including and adjacent these passages.

Inward movement of the plunger 5 on the injection stroke rst causes the fuel pressure inlet port 21 to be closed by the circumferential edge 53 of the working face of the plunger. This causes by-pass of fuel from the pumping space I4 through the' by-pass and drain port 29 and passage 61 and the return of fuel and any vapor to the fuel tank until the inclined edge 56 of the plunger slot 55 closes the by-pass port. This causes an increase in fuel pressure in the pumping space |4 sufficient to unseat the check valve 2| and causes injection of fuel through the nozzle spray openings 25 into the engine combustion space. Injection of fuel continues until both ports are next uncovered simultaneously by the circumferential edge 51 of the pressure relief groove 5| in the plunger which causes prompt relief of pressure in the pumping space through these ports. As pressure is applied to the pressure inlet port 21 the path of least flow resistance i of fuel to relieve this fuel pressure is through the by-pass and drain port 29 and fuel and any vapor from the top of the pumping space |4 is caused to again circulate through this space, plunger groove 5|, slot 55 and flow to the tank through the by-pass and drain port 29 and passage 61. This prompt relief of pressure causes prompt reseating of the check valve 2| thereby preventing after-dribble of fuel through the spray openings 25 in the nozzle 1. The spring 3| then causes the return of the plunger 5 on the filling stroke, the movement being limited by the plunger actuating and motion limiting means. This causes simultaneous and momentary closure of the ports 21 and 2S by the edge 51 on the plunger and reopening of the port 29 by the inclined edge 56 of the plunger before reopening of the pressure inlet port 21 by the edge 53 to again cause circulation of fuel through the pumping space and complete refilling thereof by the fuel.

It will be evident that the farther the inclined edge is rotated to the right, as viewed in Figure l, by means of the control arm 41, the earlier the start of fuel injection and the greater the amount of fuel injected per injection stroke of the plunger as relief of pressure and the end of injection occurs at the same point in the plunger injection stroke. Rotation of the plunger in the opposite direction sufficient to cause the relief slot 55 to register with the by-pass and drain port 29 prevents closing off of the pumping space by the plunger and no fuel will be injected. This is the engine stop or shut down position of the plunger. As previously explained the ports 21--29 in the pump cylinder are formed by a passage extending diametrically through the cylinder and cylinder bore and they are accordingly spaced apart. This passage is easily formed by drilling one hole through the cylinder. If desired, in order to vary the amount of fuel injected per plunger stroke for a given angular adjustment of the plunger by the arm 41, the ports may be angularly spaced apart a different amount and the angulaiity of the inclined edge of the plunger may be changed to suit.

The ports and mounting of fuel pump shown in Figures 3 and 4 with exception of certain details, indicated by primed character references, are similar to those of the pump shown in Figures 1 and 2. The body or cylinder of this pump is provided with an axial bore 3' and a diametral passage extending therethrough to form a pressure inlet port 21' and a drain and by-pass port 29. The pressure inlet port 21 is adapted to be connected to a source of fuel pressure and the drain and by-pass port is adapted to be connected to a drain and return to a fuel tank by suitable pipe connections, not shown, threads being provided in the outer enlarged diameter portions of the ports for this purpose.

The ports 21 and 29 open into a pumping chamber |4' formed between the plunger 5 and the valve seat Il, which together with the check valve housing 9, and nozzle 1, are secured to the cylinder I by a cap nut I3 in a similar manner to that described previously.

The plunger return spring 3| is supported at one end on a retaining washer 31' bearing on the thrust bearing 43 which is supported on a flange 45 of the cylinder The other end of the spring 3| bears on a retaining washer 33 having an integral operating arm 41. The washer 33 is nonrotatably secured to the outer end of the plunger by means of the flat 4 provided thereon and is retained on the plunger by the key 35 in the slot 36 of thc plunger. The operating arm 41 of the washer 33 serves to rotate the plunger relative to the cylinder bore. A suitable connection, not shown, in sliding contact with the arm 41 and operated by manual control means or the engine governor causes angular movement oi the washer 33 and plunger 5' as these parts reciprocate.

The above described fuel pump is mounted in a counterbore 59 of an engine cylinder head 6|' from which an opening 63 extends to the engine combustion chamber. Suitable clamping and positioning means on the cylinder head engage diametrically spaced portions 13 and 14 on the cylinder to hold the tapered seat I3 of the cap nut I3 on a complementary tapered seat on the inner end of the counterbore. It will be noted that with this mounting arrangement no fuel circulating space is provided between the pump and engine cylinder head, except for this the operation of the pump shown in Figures 3 and 4 is identical to that previously described and shown in Figures 1 and 2. The spacing of the ports and the inclination of the edge of the plunger may be changed in the same manner and for the purpose previously described.

I claim:

1. In a fuel injection device, a first conduit leading from a source of fuel under pressure and a second conduit leading to a relatively low pressure receiver, a vertical pump cylinder interposed between said conduits, a fuel inlet port in an upper portion of said cylinder communieating with said first conduit, a fuel outlet port ln said upper portion of said cylinder at substantially the same level as said inlet port communicating with said second conduit and circumferentially spaced from said inlet port, a fuel discharge opening in the bottom of said cylinder having a fuel injection nozzle directly associated therewith, a reciprocable and rotatable cylindrical plunger in said cylinder, said plunger having an annular groove in the plunger periphery upwardly spaced from the plunger face, said plunger periphery having a slot extending from said face to said groove, said slot having an oblique side and decreasing in width upwardly from said face, said plunger having said slot in generally vertical alignment with said outlet port and reciprocable from a position wherein said face is above said ports whereby said cylinder is purged of the fuel vapors in its upper portion to another position wherein said groove registers with said ports whereby said cylinder may be relieved of plunger induced pressure, said plunger permitting fluid flow from said first conduit to said second conduit in either of said positions, means for turning said plunger in said cylinder to vary the pump capacity, fuel filtering means carried by said pump cylinder and enclosing said inlet and outlet ports, said fuel injection nozzle being disposed directly adjacent to said fuel discharge opening, and a member secured to said cylinder in clamping relation to said lter means for holding said filtering means and said fuel injection nozzle in fixed relation to said cylinder.

2. In a fuel injection device, a rst conduit leading from a source of fuel under pressure and a second conduit leading to a relatively low pressure receiver, a vertical pump cylinder arranged for mounting in a cylinder head and interposed between said conduits, a fuel inlet port in an upper portion of said cylinder communieating with said rst conduit, a fuel outlet port in said upper portion of said cylinder at substantially the same level as lsaid inlet port communicating with said second conduit and circumferentially spaced from said inlet port, a fuel discharge opening in the bottom of said cylinder having a fuel injection nozzle directly associated therewith, a reciprocable and rotatable cylindrical plunger in said cylinder, said plunger having an annular groove in the plunger periphery upwardly spaced from the plunger face, said plunger periphery having a slot extending from said face to said groove, said slot having an oblique side and decreasing in width upwardly from said face, said plunger having said slot in generally vertical alignment with said outlet port and reciprocable from a position wherein said face is above said ports whereby said cylinder is purged of thefuel vapors in its upper portion to another position wherein said groove registers with said ports whereby said cylinder may be relieved of plunger induced pressure, said plunger permitting fluid flow from said first conduit to said second conduit in either of said positions, means for turning said plunger in said cylinder to vary the pump capacity, a member secured to said cylinder to hold said nozzle in fixed relation to the cylinder, means providing a passage between said member and the cylinder head and interconnecting said conduits, said passage permitting fluid flow from said first conduit to said second conduit irrespective of the position of said plunger whereby a cooling of said injection device to retard vapor formation is effected and a continuous purging of vapor is afforded, fuel ltering means carried by said pump cylinder and enclosing said inlet and outlet ports, a fuel injection nozzle disposed directly adjacent to said fuel discharge opening, and a member secured to said cylinder in clamping relation to said filter means for holding said filtering means and said fuel injection nozzle in fixed relation to said cylinder.

CLYDE W. 'I'RUXEIL, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,981,913 Fielden Nov. 27, 1934 2,090,351 Heinrich et al. Aug. 17, 1937 2,131,228 LOrange Sept. 27, 1938 2,131,779 Zwick et al. Oct. 4, 1938 2,144,861 Truxell, Jr. Jan. 24, 1939 2,144,862 Truxell, Jr. Jan. 24, 1939 2,163,313 Voit June 30, 1939 2,192,372 Buckwalter Mar. 5, 1940 2,192,387 Schlaupitz Mar. 5, 1940- 2,272,300 Johnston Feb. 10, 1942 2,296,357 Links et al Sept. 22, 1942 2,350,434 Wallgren et al June 6, 1944 2,380,148 Camner July 10, 1945 OTHER REFERENCES American-Bosch Fuel Injection Equipment, copyright 1937, United American Bosch Corporation, pages 7 and 9. 

